1. Field of the Invention
The present invention relates to a method of treating lumens, cavities, and tissues of the body with a liquid delivered with the use of ultrasound.
2. Description of the Related Art
Various infections, conditions, ailments, and diseases (hereafter collectively referred to as “maladies”) of the body are difficult to treat pharmacologically due to inaccessibility of the site of the malady to pharmacologically active compounds (commonly referred to as “drugs”) such as, but not limited to, chemical compounds, chemicals, small molecules, proteins, genes, and/or any combination thereof. Such sites include body lumens and body cavities such as, but not limited to, the urethra, sinuses, vagina, uterus, outer ear, lungs, thoracic cavity, and colon, and poorly vasculated tissue such as, but not limited, to bones. Though commonly considered otherwise by those outside of the biological arts, lumens and body cavities are outside of the body. This somewhat paradoxical statement can best be understood by considering the path an orally taken drug travels to reach the urethra, a component of the urinary tract.
A pill containing the drug is first dissolved in the stomach and/or small intestine after being swallowed, thereby liberating small drug molecules. The small drug molecules are then carried into the cells forming the walls of the small intestine by transport molecules on the cells' surfaces. Alternatively the drug molecules may pass directly into the cells of the small intestine on their own by either diffusing through cellular membranes or passing through pores located within the cellular membranes. Once within the cells forming the walls of the small intestine, the drug molecules are transported by similar mechanisms into the patient's blood stream. The drug molecules then spread throughout the patient's entire blood stream where they are subjected to degradation and/or inactivation by various elements within the blood. The blood stream also transports the drug molecules to potential sites of degradation, inactivation, and/or excretion such as, but not limited to, the kidneys and liver. Despite dilution by wide spread distribution, inactivation, degradation, and/or excretion, some of the drug molecules reach areas of the blood stream adjacent to the urethra. However, to effectively treat a malady within the urethra, the drug must be taken out of the bloodstream by the cells forming the urethra and then deposited into the open space of the urethra. Drug molecules may also reach the urethra by excretion into the urine, which flows through the open space of the urethra. Unfortunately, the urine is not kept at a constant pH, and may become sufficiently acidic or basic as to inactivate and/or degrade the drug molecules.
With respect to maladies within poorly vasculated and/or perfused tissue, pharmacological treatment is limited by a poor blood supply. Most methods of drug delivery into the body rely upon the blood stream to deliver the drug molecules to the site of the malady to be treated. Consequently the amount of drug delivered is positively related to the amount of blood delivered to the site of the malady. Therefore, a location or tissue of the body that receives a diminished, reduced, compromised, or small supply of blood is less accessible to pharmacological treatment. Various medical devices and procedures have been developed to supplement pharmacological treatment of maladies located within lumens, open body cavities, and/or poorly perfused tissues.
Catheter drug delivery methods and devices have been developed to overcome the limitations of pharmacological treatment. Inserting catheters into lumens or body cavities and injecting a drug through or from the catheters gives pharmacologically active compounds access to the site of a malady. Running a catheter through a small or narrow body lumen, such as the urethra, can be uncomfortable for the patient. Inflicting injury while inserting the catheter can create serious complications such as allowing an infection on the inner wall of the lumen or body cavity to enter the blood stream, thereby spreading the infection throughout the body. Furthermore, finding the site of the malady to be treated, while inserting the catheter, can be difficult.
To get past the delivery limitations of drugs for the treatment of maladies within shallow lumens or cavities of the body, creams and other medical ointments have been developed. The cream or ointment is spread on the walls of the cavity with a finger, swab, or similar device. Though these creams and ointments can be effective, their use is generally not preferred by the patient as they can be messy, leak out, and are often unpleasant to apply.
Delivering drugs to open body cavities and/or lumens not sufficiently accessible as to permit the application of creams, such as the sinuses, has been accomplished with various spray and/or misting devices. Exemplar devices well known in the art are nasal sprays and inhalers. Generating a spray or mist through the use of pumps or aerosols, it is difficult to utilize nasal sprays and inhalers to deliver drugs deep within an open cavity. The difficulty in achieving deep drug delivery is due to the low pressure, low velocity sprays generated by these devices. Generation of the spray or mist is generally accomplished by pressurizing the drug to be delivered and then forcing the drug through a small orifice. As to avoid damaging tissue within the cavity or lumen into which the drug is to be delivered, low pressure is used to drive drug delivery. Because pressure is the only force driving drug delivery, the use of low pressure creates a low velocity spray limiting the depth of drug penetration. Consequently, it is difficult to deliver drugs from such devices to sites of maladies deep within body cavities or lumens.
Preserving the integrity of bones, particularly bone marrow, is critically important for maintaining patient health, because bones are the site of red and white blood cell synthesis. Maladies within the bones, such as leukemia and/or osteomyelitis, can result in anemia and a compromised immune system. Treating such conditions often involves painful surgery due to the inability of drugs to adequately penetrate bone tissue. In the case of leukemia, the patient is often treated with painful bone marrow transplants during which unhealthy bone marrow is replaced with healthy bone marrow from a donor. With respect to the treatment of osteomyelitis, surgical debridement is the principal therapy. During the surgery, the bone is opened and the diseased tissue is scrapped away. The debridement procedure often leaves a large bony defect (dead space). Poorly vascularized, the presence of a dead space predisposes the patient to persistent infections. Consequently, dead bone tissue must be replaced with durable vascularized tissue. Debridement may need to be followed by stabilization such as external or internal fixation. Internal fixation devices often become infected resulting in painful complications to the patient. External fixation is labor intensive and requires an extended period of treatment averaging 8.5 months.
Ultrasound drug delivery devices have been developed in efforts to overcome some of the limitations of drug therapy. U.S. Pat. No. 5,405,614 to D'Angelo et al., U.S. Pat. No. 5,415,629 to Henley, U.S. Pat. No. 5,421,816 to Lipkovker, U.S. Pat. No. 5,538,503 to Henley, U.S. Pat. No. 5,658,247 to Henley, U.S. Pat. No. 5,667,487, to Henley, U.S. Pat. No. 5,947,921 to Johnson et al., U.S. Pat. No. 6,041,253 to Kost et al., U.S. Pat. No. 6,190,315 to Kost et al, U.S. Pat. No. 6,234,990 to Roe et al., U.S. Pat. No. 6,322,532 to D'Sa et al., and U.S. Pat. No. 6,491,657 to Rowe et al describe transdermal ultrasound drug delivery devices utilizing ultrasonic energy to drive a drug across the patient's skin. However, delivering drugs to deep tissue such as, but not limited to, bone marrow is difficult to accomplish with these devices. U.S. Pat. No. 6,601,581 to the present inventor describes an ultrasound inhaler utilizing ultrasonic energy to create a fine drug mist. Though effective at delivering drugs to the lungs and bronchia, this device is incapable of creating a spray of sufficient velocity to enable drug delivery deep within lumens and cavities of the body.
Though drugs are often effective in treating various maladies of the body, they are not always necessary. Many maladies of the body can be treated simply by washing and/or flushing the affected area. Washing and/or flushing with simple, drug free fluids such as, but not limited to, saline or water has the benefit of avoiding the various side effects and complications drugs may possess. Unfortunately, the practicality of washing and/or flushing body cavities, body lumens, and poorly perfused tissues is hindered, as is drug delivery, by the lack of devices capable of delivering a liquid deep into the affected lumens, cavities, and poorly perfused tissues.
The difficulty in achieving therapeutically effective drug concentrations or permit the washing and/or flushing of body lumens, body cavities, and poorly perfused tissues with present devices and traditional routes of administrations creates a need for a new method of treating body lumens, body cavities, and poorly perfused tissues.